(1124) Hypercapnia Highs and Lows: Navigating Risks and Outcomes of Severe Hypercapnic Respiratory Failure

Introduction: Hypercapnic respiratory failure (RF) is a common indication for ICU admission and invasive ventilation. Little is known whether patients presenting with more severe hypercapnic RF (PCO2 >90mmHg) differ from patients with less severe hypercapnic RF (PCO2 70-90mmHg) in regard to demographics, etiology and clinical course. We compared the rate of intubation, ventilator free days and mortality in patients with severe hypercapnic RF to those with less severe hypercapnia.

Methods: A single center retrospective cohort study compared patients with severe hypercapnic RF (PCO2 >90 mmHg within 48 hours of admission) and patients with less severe hypercapnic RF (PCO2 70-90mm Hg). Patient demographic data and SOFA scores were collected. Primary outcomes were in-hospital mortality, endotracheal intubation and ventilator-free days (number of days alive and off ventilator for first 28 days). Data expressed as mean±SD. Χ2 used for categorical values; student’s t-test for continuous variables.

Results: 133 patients were included for analysis, 51 had severe hypercapnic RF; PCO2>90mmHg (study group) and 82 with less severe hypercapnic RF; PCO2 70-90mmHg (control group). There was no difference in baseline demographics: age of 56±15 years vs. 61±12 years (p < 0.01), 53% were male vs. 44% (p=0.4), BMI of 40±16 kg/m2 vs. 38±15 (p=0.30), but presenting serum bicarbonate was 36±8 meq/L vs. 32±8 (p < 0.01), Charlson Index was 4.2±3.0 vs 4.5±2.2 (p=0.58), SOFA score was 5.2±4.3 vs. 5.5±3.7 (p=0.73) in the study and control group respectively. There was no significant difference between the groups in any of the outcomes: Comparing the study group to the control group, 7 (14%) vs. 22 (27%) died (p=0.13), 30 (58%) vs. 40 (50%) required endotracheal intubation (p=0.34), with average ventilator-free days were 21±10 vs. 20±12 (p=0.40).

Conclusions: Patients with severe hypercapnic RF whose PCO2 exceeded 90mmHg were younger but had similar SOFA scores compared to those with less severe hypercapnia. Overall, both groups had similar BMI, rates of endotracheal intubation and ventilator-free days.Patients with more severe hypercapnia had higher presenting serum bicarbonate with a trend towards lower mortality that did not reach statistical significance.